/Engine/Plugins/Online/OnlineSubsystemUtils/Source/OnlineSubsystemUtils/Public/OnlineBeaconHost.h
Handler for messages sent through a remote connection's control channel not required to handle the message, but if it reads any data from Bunch, it MUST read the ENTIRE data stream for that message (i.e. use FNetControlMessage::Receive())
virtual void NotifyControlMessage ( [UNetConnection](API\Runtime\Engine\Engine\UNetConnection) * Connection, uint8 MessageType, [FInBunch](API\Runtime\Engine\Net\FInBunch) & Bunch )